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Astron. Astrophys. 343, 33-40 (1999)

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5. Summary

We have presented BeppoSAX observation of the BLRG 3C 390.3. The X-ray data are well represented by an absorbed hard power law, plus a narrow [FORMULA] iron line and a Compton reflection component. No X-ray soft excess is required by the data in agreement with the results of previous X-ray satellites.

Considering also that a weak blue bump seems to characterize this source, we conclude that:

  1. Beamed non-thermal X-ray continuum does not significantly contaminate the nuclear emission.

  2. Material able to absorb and thermalize the X-rays is not present close to the X-ray source (otherwise we would observe a luminous UV to soft X-ray thermal component).

  3. However, such material must lie at some distance and intercept a fraction [FORMULA] 50% of the X-rays (otherwise we would not observe any reflection hump and iron line).

The model that better accounts for these results is a hot, X-ray emitting inner accretion flow. Roughly half of the X-ray radiation illuminates outer, cold, IR emitting material, possibly in the form of a warped disk and/or a dusty torus, producing the reflection hump and the narrow emission line. At this stage, it is premature to assess the nature of the hot inner flow. Different models (i.e., the ion-supported torus, the ADAF, or the SLE) could possibly be compared by studying UV-to-X-ray spectral variability on long time scales. For this aim, further broad-band observations are most welcome.

Finally we have presented a study of the time variations of [FORMULA], based on all the available historical data. We have shown, for the first time, that the column density in this source changes on time scale of years independent of variations in the X-ray flux. It is difficult to relate the variations of the absorber to changes of the ionization state of the medium along our line of sight. Geometrical modifications of the absorber would better account for the long term [FORMULA] variations.

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© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999